Halon Replacements - ACS Publications - American Chemical Society

Chapter 9

Halogenated Fire Suppression Agents

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Mark L. Robin Fluorine Chemicals Department, Great Lakes Chemical Corporation, 1801 Highway 52 Northwest, West Lafayette, IN 47906

This paper summarizes recent efforts by the industrial, academic and governmental sectors in the search for suitable replacements for Halons 1301 and 1211. The current status of potential replacement agents with regard to their fire suppression effectiveness, large scale testing, and regulatory agency approvals is detailed. This paper reviews recent efforts in the development of replacements for the widely employed fire suppression agents Halon 1301 and Halon 1211. During the past 30 years, the use of these highly efficient, clean, nontoxic fire suppression agents has prevented the loss of human life, and these agents currently protect billions of dollars worth of equipment worldwide. However, because of their recent implication in the destruction of stratospheric ozone, the production and use of these life-saving agents is being severely restricted. As a result, intensive research efforts have been undertaken in the industrial, academic, and governmental sectors with the goal of developing replacements for these agents. This paper reviews these efforts in the area of halon replacements, covering the period from the late 1980s to the present. Several earlier reviews discussing the use of halogenated species as fire suppressants have been published, and the interested reader is directed to these past reviews (7-6). Historic Halogenated compounds have been employed as fire suppression agents since the early 1900s when hand-held extinguishers containing carbon tetrachloride were introduced (6). In the late 1920s methyl bromide was found to be more effective than carbon tetrachloride, and was widely employed as a fire suppressant agent by the British in the late 1930s in aircraft protection, and by the German military during World War II for aircraft and marine applications. Suppression systems employing bromochloromethane were also developed in the late 1930s, and were employed by the German Luftwaffe. Bromochloromethane was evaluated in the United States during the late 1930s to the late 1940s and was eventually employed by the US Air Force (7). 0097-6156/95/0611-0085$12.00/0 © 1995 American Chemical Society In Halon Replacements; Miziolek, A., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.


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Although extremely effective as fire suppression agents, the relatively high toxicities of methyl bromide and bromochloromethane prompted the US Army to initiate a research program to develop an extinguishing agent which retained the high effectiveness of these agents but was less toxic. Army sponsored research at Purdue University evaluated over 60 candidate agents, most of which were halogenated hydrocarbons, for both fire suppression effectiveness and toxicity (S). As a result of these studies, four agents were selected for further evaluation: bromotrifluoromethane (Halon 1301), bromochlorodifluoromethane (Halon 1211), dibromodifluoromethane (Halon 1202), and 1,2-dibromotetrafluoroethane (Halon 2402). These further evaluations ultimately led to the widespread use of Halon 1301 in total flood and small portable applications, and the use of Halon 1211 in streaming applications. Halons 1301 and 1211 are characterized by high fire suppression efficiency, low toxicity, low residue formation following extinguishment, low electrical conductivity, and long-term storage stability. Because the agents produce no corrosive or abrasive residues upon extinguishment, they are employed to protect areas such as libraries and museums, where the use of water or solid extinguishing agents could cause secondary damage equal to or exceeding that caused by direct fire damage. Because they are nonconducting they can be used to protect electrical and electronic equipment, and because of their low toxicity they may be employed in areas where egress of personnel may be undesirable or impossible. Because of their unique combination of properties, the halons have served as near ideal fire suppression agents during the past 30 years. However, due to their implication in the destruction of stratospheric ozone, the Montreal Protocol of 1987 identified Halon 1301 and Halon 1211 as two of a number of halogenated agents requiring limitations of use and production, and an amendment to the original Protocol resulted in the halting of production of Halons 1301 and 1211 on January 1, 1994 (9). Halon Replacements The ideal halon replacement, in addition to possessing the desirable characteristics of the halons, is required to have a much lessened environmental impact with regard to its potential for ozone depletion, and also with regard to its potential for contributing to global warming. Hence, one possible set of requirements for the ideal halon replacement is as follows: 1. 2. 3. 4. 5. 6. 7. 8.

Highly efficient fire suppression Nontoxic Clean (no residue) Nonconducting Storage stable Zero ozone depletion potential (ODP) Zero global warming potential (GWP) Manufacturable at reasonable cost

To date no replacement agent, halogenated or otherwise, has been found which satisfies all of the above requirements, although replacements have been found that match many of the above criteria. The various agents investigated as possible halon

In Halon Replacements; Miziolek, A., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1997.

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replacements are discussed below, where they are divided into the chemical class of compound examined. Preliminary testing of the fire suppression characteristics of a potential candidate is typically performed employing the laboratory-scale cup burner apparatus, with n-heptane as the fuel. The cup burner apparatus has been described in detail by Hirst and Booth (10), and more recently by Sato, et. al. (77).


Bromine-Based Halon Replacements Hydrobromofluorocarbons (HBFCs). Perhaps the first compounds considered by researchers for the replacement of the halons were the hydrobromofluorocarbons (HBFCs). The bromine atom is known to provide high fire suppression characteristics, and the fluorine atom is known to impart stability and volatility. The introduction of hydrogen into the molecular structure provides a means for tropospheric destruction of the molecule via abstraction of the hydrogen atom by tropospheric hydroxyl radicals. Destruction of the HBFC molecule in the troposphere would prevent the bromine atom from reaching the stratosphere, where it could participate in the destruction of ozone. Table I shows the properties of those HBFCs receiving attention in the scientific community. Laboratory and large scale testing of the leading candidates in this class, CHBrF2 (72-75) and CF3CHBrF (16) demonstrated that these agents could indeed provide fire suppression capabilities essentially equal to that of the halons.

Table I. Hydrobromofluorocarbons Ext. Conc. % v/v ODP MW Formula bp(°C) 1.8^ 65b CF3CF1FCF3 , and HCFC Blend A . Employing standard fire growth rates and the results of their intermediate scale testing, DiNenno, et. al., have developed scaling factors for HF production as a function of fire size and have employed these to predict expected H F concentrations for slow, medium and fast fire growth rates (52). Rapid detection and discharge were concluded to result in decreased production of HF. Full scale testing of CHF3, n-C4FiQ, CF3CHFCF3, and the HCFC Blend A were carried out by Coast Guard personnel in 1994, and full scale testing of CHF3, n-C4Fio and CF3CHFCF3 on the Navy's full scale fire research ship, the ex-USS Shadwell, were completed in late 1994. A general observation from these intermediate and large scale tests is the increased production of the decomposition product HF from the HFCs and PFCs compared to Halon 1301. In general, for a given fire scenario, HF levels produced upon extinguishment by the HFCs and PFCs are approximately 5-10 times those formed upon extinguishment by Halon 1301. It is important to keep in mind, however, that many of these tests involve extremely large fires under very specialized conditions such that extinguishment by Halon 1301 itself can lead to the production of H F in amounts approaching ten thousand parts per million. For some of these fires it is questionable whether these high HF levels have any significance when consideration is given to the enormous output of heat and combustion products associated with these large fires and the damage to equipment and personnel these factors alone could cause. The generation of HF from the HFCs and PFCs can be limited by employing a more ?


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rapid discharge , and this forms the basis for the National Fire Protection Association requirement under NFPA 2001 that such agents be discharged in less than 10 seconds. More rapid detection and system actuation can also minimize HF generation. NIST has carried out extensive testing of C2F6, n-C3Fg, n-C4Fio» cycloC F , C F C F H , C F C H F , CF3CHFCF3, CF3CH2CF3, CHC1F , CF3CHCIF and a CH2F2/CF3CF2H blend, including fire suppression, agent discharge, and compatibility studies as part of its program to develop agents for engine nacelle and dry bay applications (21). NIST is currently recommending n ^ F g , CF3CF2H and CF3CHFCF3 for full scale testing by the US Air Force in dry bay and engine nacelle applications. Fire suppression testing of CF3CHFCF3 on typical electronic data processing (EDP) facility fires (wire bundles, magnetic tapes, PC boards) has demonstrated that minimal HF (< 50 ppm) is produced upon extinguishment of these Class A fires (53). As the tests were conducted under worst case conditions of zero air movement and hence long detection times, real world fire scenarios are expected to produce even less HF. This is in agreement with the conclusion of Skaggs and Moore (40) that for typical computer rooms and offices HF concentrations from suppression with the HFCs and PFCs at their design concentrations of cup burner plus 20% will be comparable to that observed with Halon 1301. 4


HALON REPLACEMENTS

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Regulatory and Approval Agency Status In order to obtain widespread acceptance, a halon replacement must obtain the necessary governmental and fire protection industry approvals. In the United States, governmental approval of halon replacements is granted under the US E P A SNAP program. The National Fire Protection Association (NFPA), through its NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems, establishes the minimum requirements for total flooding clean fire extinguishing systems. In addition, many end users require that fire suppression systems employing halon replacements be listed or approved by independent testing agencies, for example Underwriters Laboratories or Factory Mutual. The current status of the halogenated fire suppression agents with respect to regulatory and listings/approvals agencies is discussed below. US E P A S N A P Program (19). Streaming Agents. Halogenated fire suppression agents currently approved for use as streaming agents under the US EPA Significant New Alternatives Policy (SNAP) are shown in Table VIII. Under the current SNAP program, HCFCs cannot be employed in residential extinguishers, but are allowed in commercial, watercraft and aircraft use in portables. Under SNAP, PFCs are acceptable for nonresidential use only when other alternatives are not technically feasible. Phase out of CHBrF2 is scheduled for January 1, 1996, and the HCFCs are currently scheduled for phase out in 2030. Approval of HFC-227ea in streaming applications is currently pending. Flooding Agents. Halogenated fire suppression agents currently approved for use as total flooding agents under the US EPA SNAP program are shown in Table IX. Phase out of CHBrF2 is scheduled for January 1, 1996, and the HCFCs are currently


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scheduled for phase out in 2030. Although all the agents listed in Table IX are acceptable under SNAP as total flood agents in unoccupied areas, under the criteria of NFPA 2001 only CHF3, CF3CHFCF3, HCFC Blend A and n-C4Fio are acceptable for use as total flood agents in normally occupied areas.

Table VIII. Streaming Agents Acceptable Under SNAP SNAP Acceptability Formula Trade Name Agent HBFC-22B1 CHBrF Great Lakes "FM-100" acceptable HCFC-123 CF CHC1 DuPont "FE-232" acceptable HCFC-124 CF3CHCIF DuPont "FE-241" acceptable HCFC Blend B a American Pacific "Halotron acceptable I" HCFC Blend C b N A F G "NAF P-III" acceptable HCFC Blend D d NAFG "Blitz" acceptable FC-5-1-14 n-CfiFu 3M Co. "CEA 614" acceptable Primarily HCFC-123. ^HCFC-123, HCFC-124, HFC-134a, and proprietary additive. North American Fire Guardian. HCFC-123 plus proprietary additive. P F C s acceptable only when other alternatives are not technically feasible.


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Table IX. Total Flooding Agents Acceptable Under SNAP SNAP Acceptability Trade Name Agent Formula acceptable HBFC-22B1 CHBrF Great Lakes "FM-100" acceptable HCFC-124 DuPont "FE-241" CF3CHCIF acceptable N A F G "NAF S-III" HCFC Blend A b acceptable CHF3 DuPont "FE-13" HFC-23 acceptable DuPont "FE-25" CF CHF HFC-125 acceptable^ 3M Co. "CEA 410" FC-3-1-10 n-C4F acceptable HFC-227ea CF^CHFCF^ Great Lakes "FM-200" Cannot be employed as total flood agent in occupied areas under NFPA 2001. ^HCFC-123, HCFC-124, HFC-134a, and additive. North American Fire Guardian. dPFCs acceptable only when other alternatives are not technically feasible. a

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N F P A 2001 (28). NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems contains minimum requirements for total flooding clean fire extinguishing systems. Halogenated agents addressed in the standard are C H B r F , CHF3, CF3CHCIF, C F C F H , HCFC Blend A , CF3CHFCF3 and n - C F i . NFPA 2001 requires that for use as a total flooding agent in a normally occupied areas, the design concentration cannot exceed the N O A E L of the agent. Hence, the only halogenated agents approved for use in total flood systems for normally occupied areas under NFPA 2001 are CHF3, CF3CHFCF3, n-C4Fio and HCFC Blend A . 2

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Underwriters Laboratories/Factory Mutual. Currently U L International listings and Factory Mutual approvals have been granted for only two halogenated fire suppression agents, CF3CHFCF3 and n-C4Fio- These listings and approvals follow the completion of stringent testing of fire suppression, system operation and materials compatibility, conducted under the direction of Underwriters Laboratories and Factory Mutual.


The Future Based upon a consideration of current and anticipated future legislation, it is generally accepted that viable long term replacements for Halon 1301 and Halon 1211 will be required to have a zero ODP. Choices of halogenated hydrocarbons are thus narrowed to the classes of PFCs and HFCs. As happened in the case of the ozone depletion issue, concern over global warming issues will likely increase with the passage of time, and may ultimately narrow the choice even further, leaving only the HFCs as acceptable halogenated fire suppression agents. Indications of this trend are already apparent from an examination of the US EPA SNAP policy, which currently allows the use of PFCs only when other alternatives are not technically feasible. Literature Cited 1. 2. 3.

4. 5. 6. 7. 8. 9. 10. 11. 12.

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Halogenated Fire Suppressants, Gann, R. G., Ed.; ACS Symposium Series 16; American Chemical Society: Washington, D C , 1975. McHale, E . T. Fire Res. Abstracts and Reviews 1969, 11, 90. Ford, C. L . In Halogenated Fire Suppressants; Gann, R. G., Ed.; A C S Symposium Series 16; American Chemical Society: Washington, 1975; pp 163. Engibous, D. L . ; Torkelson, T. R. "A Study of Vaporizable Extinguishants"; W A D C Technical Report 59-463, 1960. Musik, J. K.; Williams, F. W. "The Use of Halons as Fire Suppressants-A Literature Survey"; Naval Research Laboratory, 10/5/77. Wharry, D.; Hirst, R. Fire Technology: Chemistry and Combustion, Inst. Fire Engineers: Leichester, England, 1974. Strasiak, R. "The Development History of Bromochloromethane"; W A D C Technical Report 53-279, 1954. "Final Report on Fire Extinguishing Agents for the Period September 1, 1947 to June 30, 1950"; Purdue Research Foundation, Contract W-44-099-eng-507. Harrington, J. L. NFPA Journal 1993, March/April, 38. Hirst, R.; Booth, K. Fire Technology 1977, 13, 296. Saso, Y.; Sato, Y.; Iwata, Y . Ibid. 1993, 29, 22. Robin, M . L . "FM-100: An Efficient Halon Alternative For Use in Portable and Total Flooding Extinguishing Systems," Presented at the 10th Winter Fluorine Conference, ACS Fluorine Division, St. Petersburg Beach, F L , February 1991. Robin, M . L . "Halon Alternatives: Laboratory Evaluation by the Cup Burner Method," Presented at the 200th National A C S Meeting, Washington, D C , August 1990. Robin, M . L . "Evaluation of Halon Alternatives," Proceedings of the 1991 Halon Alternatives Technical Working Conference, Albuquerque, N M , April 30-May 1, 1991.


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Robin, M . L . "Large Scale Testing of Halon Alternatives," Proceedings of the 1991 International CFC & Halon Alternatives Conference, Baltimore, M D , Dec. 3-5, 1991. Jones, P.; Winterton, N . "Clean Agent Fire Extinguishants: Further Study of Breakdown Products," Proceedings of the 1991 International CFC & Halon Alternatives Conference, Baltimore, M D , December 3-5, 1991. Nimitz, J. S.; Skaggs, S.; Tapscott, R. E . "Next-Generation High-Efficiency Halon Alternatives," Proceedings of the 1991 International Conference on CFC and Halon Alternatives, Baltimore, M D , December 3-5, 1991. Robin, M . L . "Halon Alternatives: Recent Technical Progress," Proceedings of the 1992 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 12-14, 1992. Federal Register, Vol. 59, No. 53, Friday, March 18, 1994. Smart, B. E . ; Fernandez, R. E . "Fluorinated Aliphatic Compounds," In Kirk -Othmer Encyclopedia of Chemical Technology, 4th edition, Vol. 11, John Wiley, New York, 1994. Grosshandler, W. L.; Gann, R. G.; Pitts, W. M . "Evaluation of Alternative In flight Fire Suppressants for Full-Scale Testing in Simulated Aircraft Engine Nacelles and Dry Bays," NIST Special Publication 861, April 1994. Robbins, B. H. J. Pharm. Exp. Ther. 1946, 86, 197. Davies, R. H . ; Bagnall, R. D.; Bell, W.; Jones, W. G. M . Int. J. Quantum Biology Symp. 1976, 3, 171. Tapscott, R. E . "Replacement Agents - An Historical Overview," Proceedings of the 1992 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 12-14, 1992. Robin, M . L.; Iikubo, Y . U.S. Patent 5,080,177, 1992. Skaggs, S.; Heinonen, E . ; Tapscott, R. E . ; Smith, E . D. "Research and Development for Total Flood Halon 1301 Replacements for Oil and Gas Production Facilities at the Alaskan North Slope," Proceedings of the 1991 International Conference on CFC and Halon Alternatives, Baltimore, M D , December 3-5, 1991. Bannister, W. W.; Jahngen, E . G.; Kibert, C.; Nelson, D.; Mitchell, B.; Dierdorf, D. "Recent Advances in Development of Non-Volatile Precursors (NVPS) to Alternate Halon Fire Extinguishing Agents with Reduced Global Environmental Impacts," Proceedings of the 1993 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 11-13, 1993. NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems, NFPA, 1994. Skaggs, S.; Tapscott, R. E.; Moore, T. A . "Technical Assessment for the SNAP Program," Proceedings of the 1992 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 12-14, 1992. Moore, T. A.; Dierdorf, D.; Skaggs, S. "Intermediate Scale (645 ft ) Fire Suppression Evaluation of NFPA 2001 Agents," Proceedings of the 1993 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 11-13, 1993. Robin, M . L.; Iikubo, Y . U.S. Patent 5,137,095, 1992. Brashear, W. T.; Vinegar, A. "Metabolism and Pharmokinetics of Halon 1211 and its Potential Replacements HCFC-123 and Perfluorohexane, " Proceedings of the 1992 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 12-14, 1992. Tapscott, R. E . ; Floden, J. "Progress Toward Halon 1211 Alternatives," Presented at Halon and Environment '90, 2nd Conference on the Fire Protecting Halons and the Environment, Geneva, Switzerland, October 1-3, 1990. 3


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HALON REPLACEMENTS Floden, J.; Tapscott, R. E . "Evaluation of Selected Perfluorocarbons as Streaming Agents," Proceedings of the 1991 International Conference on CFC and Halon Alternatives, Baltimore, M D , December 3-5, 1991. Kibert, C. J. "Fluoroiodocarbons as Halon 1211/1301 Replacements- An Overview," Proceedings of the 1994 Halon Options Technical Working Conference, Albuquerque, N M , May 3-5, 1994. McIlloy, A . "Ignition Suppression by C F B r and CF3I of H / O / A r - Mixtures: Detailed Studies of Time and Space Resolved Radical Profiles," Proceedings of the 1994 Halon Options Technical Working Conference, Albuquerque, N M , May 3-5, 1994. Nimitz, J. "Trifluoromethyl Iodide and Its Blends as High-Performance, Environmentally Sound Halon 1301 Replacements," Proceedings of the 1994 Halon Options Technical Working Conference, Albuquerque, N M , May 3-5, 1994. Solomon, S.; Ravishankara, A . R.; Garcia, R. R. J. Geophys. Res. 1994, 99, 20491. Solomon, S.; Ravishankara, A . R.; Garcia, R. R. J. Geophys. Res.1994, 99, 20929. Skaggs, S.; Moore, T. A. "Toxicological Properties of Halon Replacements," Presented at the 208th A C S National Meeting, Washington, D C , August 21, 1994. Skaggs, S.; Dierdorf, D.; Tapscott, R. E . "Update on Iodides as Fire Extinguishing Agents," Proceedings of the 1993 International C F C & Halon Alternatives Conference, Washington, DC, Oct. 20-22, 1993. Ulm, K. Spec. Chem. 1988, 8, 418. Pitts, W. M . , et al., "Construction of an Exploratory List of Chemicals to Initiate the Search for Halon Alternatives," NIST Technical Note 1279, 1990. Gann, R. G., et al., "Preliminary Screening Procedures and Criteria for Replacements for Halons 1211 and 130 1," NIST Technical Note 1278, 1990. Chemical and Engineering News, September 19, 1994, p. 31. Ravishankara, A . R.; Solomon, S.; Turnipseed, A.; Warren, R. Science 1993, 259, 194. Henne, A . L . ; Waalkes, T. P. J. Am. Chem. Soc. 1946, 68, 496. Skaggs, S.; Dierdorf, D.; Moore, T. A. "Advanced Streaming, Agent Program," Proceedings of the 1994 Halon Options Technical Working Conference, Albuquerque, N M , May 3-5, 1994. Ferreira, M . ; Pignato, J.; Pike, M . "An Update on Thermal Decomposition Product Results Utilizing PFC-410, " Presented at the International C F C and Halon Alternatives Conference, Washington, DC, 1992. DiNenno, P.; Forssell, E.; Peatross, M . ; Maynard, M . "Evaluation of Alternative Agents for Halon 1301 in Total Flooding Fire Suppression Systems," Proceedings of the 1993 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 11-14, 1993. Sheinson, R. S. "Halon 1301 Replacement Total Flooding Fire Testing: Intermediate Scale," Proceedings of the 1994 Halon Options Technical Working Conference, Albuquerque, N M , May 3-5, 1994. Hanauskas, C.; Forssell, E . ; DiNenno, P. "Hazard Assessment of Thermal Decomposition Products of Halon Alternatives," Proceedings of the 1993 Halon Alternatives Technical Working Conference, Albuquerque, N M , May 11 14, 1993. "Hazard Assessment of Thermal Decomposition Products of FM-200™ in Electronics and Data Processing Facilities," Hughes Associates, Inc., 1/16/95. 3

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Halon Replacements - ACS Publications - American Chemical Society

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